Choosing Clouds for an Enterprise –Modeling and Evaluation Ruay-Shiung Chang Department of Computer Science and Information Engineering National Dong Hwa University Hualien, Taiwan, R.O.C. rschang@mail.ndhu.edu.tw Chuan-Yu Liu, Chih-Shan Liao Department of Computer Science and Information Engineering National Dong Hwa University Hualien, Taiwan, R.O.C. aadan5@hotmail.com, toptom@mail.ndhu.edu.tw Abstract—The development of cloud computing has advanced rapidly over the past few years. Benefitting from the dynamic characteristics of cloud computing, enterprises can purchase cloud services based on different aspects in order to save operating expenses. Many companies have seen the opportunities and changes in either cloud computing service providers or cloud computing service consumers. For the latter, with so many cloud providers to choose from, there is a need for an evaluation of standards to help find the most suitable service provider. In this paper, the essential factors of enterprise clouds are discussed. An evaluation model is defined and a web based enterprise cloud selection application is implemented. Keywords—cloud computing; enterprise cloud I. INTRODUCTION Cloud computing has become the most discussed topic in many areas. Scientists have focused on cloud computing in order to produce better performance, lower energy consumptions or improve security and reliability. Enterprises see the great advantage that cloud computing can produce. One of the advantages of the enterprise cloud is to save money for the company by renting computing resources rather than buying them. According to Forrester Research [1], the global cloud computing market has reached $40.7 billion in 2011 and will grow to $241 billion in 2020. SaaS (Software as a Service) is currently dominating the cloud computing market and will likely continue to in the future. With such the cloud service market on such a large scale, there are countless cloud service providers for an enterprise to choose from. There is obviously a need for an evaluation standard to help enterprises find the most suitable cloud service provider. To define our evaluation model, first we need to discuss the essential factors of an enterprise cloud. Based on the essential factors of an enterprise cloud, a more detailed evaluation model for an enterprise cloud is defined. After that, we create a web based enterprise cloud selection application ECSS (Enterprise Cloud Selection System) to test the accuracy and reliability of our enterprise cloud evaluation model. The remainder of this paper is organized as below. In section 2 we discuss some basic background of cloud computing and analyze some of the main cloud service providers. Section 3 discusses the essential factors of the enterprise cloud in detail while we also propose an evaluation model for an enterprise cloud. In section 4, we use formulas to quantify our selection results. In section 5, we use the evaluation model to implement a web based enterprise cloud selection system. Finally our future work and conclusions are further discussed in section 6. II. RELATED WORKS What is cloud computing? There are numerous ways to describe this new technology. We can think of cloud computing as a way to deliver computing as a resource to required users over a network, which is usually the Internet. Computing resources, information and fundamental hardware can be shared to users with devices that have access to the network. For an enterprise, cloud computing can be seen as a way to improve the robustness of their company. In [2], a detailed view of cloud computing is presented. The cost of moving into cloud computing is discussed and the cost of maintaining traditional computing resources and renting cloud computing resources are compared. Some of the essential features of cloud computing are briefly discussed in [11]. In [3], the security issues of cloud computing are discussed and a solution is proposed. In [12][14], more information are discussed with regard to the security issues of cloud computing. Information related to the contractual and legal issues of cloud services are mentioned in [13]. In [4], the cost of cloud computing is discussed from the cloud service provider’s and cloud service consumer’s perspective. The strength, weaknesses, opportunities and threads of cloud computing are identified in [10]. The advantages for enterprises to embrace cloud computing are discussed in [15]. More advantages of cloud computing are written about in [16]. Finally, the essential components of the enterprise cloud from the different aspects of end-users, enterprises and cloud service providers are discussed in [17]. III. ENTERPRISE CLOUD EVALUATION MODEL AND STANDARD In cloud computing, technological perspective and enterprise perspective focus on different factors. In technological perspective, essential factors include higher performance and lower energy consumption. In enterprise 134